The goal of the UCLA-CGEP is to investigate the hypothesis that the cellular mechanisms of action identified for Putative Environmental Toxicants (PETs) contribute to a significant increase in PD risk;this project (Project 2) willfocus on investigations in Drosophila to Investigate the mechanisms of PET action and their interaction with .genetic lesions in the same cellular pathways. Epidemiological and in vitro data from our. group-have shown that exposure to PETs increases the risk of PD and suggested several potential mechanisms by which PETs may exert toxjc effects in dopaminergic.(DA) neurons: the proteaspme, microtubule function, and detoxification by aldehyde dehydrogenase (ALDH): We also have shown that altered expression of the vesicular mohoamine transporter (VMAT) affects the vulnerability of DA neurons to . neurodegeneration. The three Drosophila labs collaborating on Project 2 have extensive experience using Drosophila genetics to model neurodegenerative disorders and the contribution of environmental insults. Here, we propose to use Drosophila genetics to investigate: 1) which of the known biochemical activities of the PETs contribute to DA cell death, 2) whether PETs and genetic lesions in the same biochemical pathway can combine to increase DA cell death, and 3) how manipulation of VMAT affects the neurotoxicity of the PETs. Drugs and toxins that inhibit these processes have pleiotropic effects, and.we propose to precisely define the contribution of each pathway using molecular genetic mimics to inhibit the proteasome, microtubule function, and aldehyde dehydrogenase. The molecular genetic reagents we will use are either already available or readily made and will include RNA interference to knockdown expression of the ubiquitin activating enzyme (E1), misexpression of two well characterized dominant negative mutations.in 20S proteasome subunits, expression in DA neurons of the longest isoform of human tau, and loss of function mutations in Drosophila ALDH. The results of Project 2 and Project 1 will be used to help develop rodent models in Project 3, and^help determine biochemical pathways to be emphasized in the human genetic studies of Project 4. Fly models for PET exposure also will enable us in future aims to evaluate potential neuroprotective strategies.